raith status

Luigi Scaccabarozzi scaccag at stanford.edu
Mon Sep 6 18:32:05 PDT 2004


Hi Cole,
thanks for your answer, I developed and inspected at the optical
microscope my chip: everything seemed fine: I could see very small
stitching error in underexposed lines, but I think that it was within
specs (really hard to see). I wrote a few patterns (800 um-long
waveguides) over ~1x1.5 cm^2 and no visible errors in any of them. Some of
the lines far away from my focus points  were slightly rough but I assume
that's because I was starting to go out of focus (sample tilted).
So, in conclusion, at least at the optical microscope, everything seems
normal.

I received also a notice from another user, Charis:
>
> hi guys,
>
>       i noticed in my write today that the raith is takin unusually long.
> it even stops in empty write fields and shows 'stitching wait' for 3s.
> what is this 'stitching wait' and how do i turn it off? thanks.
>
> cheers,
> charis.
>

Can you say anything about that? It happened to me in past that some
patterns which should write fast were actually written very slow and
sometimes with errors: it looked actually like there was an error in the
interpretation of the gds pattern, although it was displayed correctly in
the editor. It's a bit complicate to explain by email, but I can call you
or send you some detailed explanations if you want. Anyway, the time
required to write those patterns seemed to be pattern- and size-depent.

That's it for now, I will be able to give you more info about the sample
in a week or so (after finishing processing it and SEM it), if you need.
Thanks
Luigi
PS: I haven't checked the beam current at all aperture yet, I'll try to do
that this week




On Fri, 3 Sep 2004, Cole Loomis wrote:

> Hi Luigi,
>
> Thank you for the system update.  I would like to hear how your exposure
> turns out, so please keep me posted.  In reference to your
> questions/comments below, my comments are in BLUE.
>
> Thanks again,
>
> Cole Loomis
> Service Engineer
> ----------------------------------
> Raith USA, Inc.
> 2805 Veteran's Hwy - Suite 23
> Ronkonkoma, NY  11779
>
> Office:  (631) 738-9500  EXT: 16
> Fax: (631) 738-2055
>
>
> -----Original Message-----
> From: Luigi Scaccabarozzi [mailto:scaccag at stanford.edu]
> Sent: Thursday, September 02, 2004 10:01 PM
> To: cl at raithusa.com
> Cc: jwc at snf.Stanford.EDU
> Subject: raith status
>
>
> Hi ... (sorry, I'm not sure how to spell your name),
> I got your voice mail. I've been away the past two days, however this is
> what I can tell you: I just started an overnight write, everything seemed ok
> (beam quality, spot size, align writefield...) except one detail: the V zoom
> factor for 100um WF, 600X,  5mm WD, 10um aperture, 10keV was 1.52 whereas
> the U zoom factor was 1.49. I remember in past the two numbers were about
> the same (~1.49). A few weeks ago we had the problem of V zoom factor
> exceeding the range (which, BTW, is close to 1.52), and we could not write
> at 600x, but only at, say 570X. After a while the problem misteriously
> disappeared and zoom V factor got back to normal values (~1.49). This time
> the V factor didn't exceed the limit, so I started the write anyway.
>
> This zoom value depends on the calibration of the Electro-Optics board;
> which was replaced last week and recalibrated over several iterations.  It
> is normal for these values to be slightly different, so if your
> align-writefield is working at a mag of 570, then leave it there.  Please
> verify that the magnification display is correct:  On the LEO PC, go to
> "Tools > User Preferences > SEM Conditions > Magnification Display"  Make
> sure this is set to "Polaroid 545".
>
> Another comment is about the current: at 10 keV, 10um , after cleaning and
> bake I would expect a current of at least 0.025nA, whereas I measured only
> 0.0175 nA... has the column already got that bad?
>
> What are the beam current values for all apertures at 10keV?  If they are
> all a little low, we could adjust the extractor voltage to increase the beam
> current.  I highly doubt that the column is already contaminated.  Since
> there were a few extractor trips on the system last week, the gun parameters
> might need some minor tweaking.
>
> Otherwise I didn't hear of any complain from other users.
> I will develop tomorrow morning and I'll be able to tell you more.
>
> I haev also one question about the piezos: I'm using small pieces (~ 1x 2
> cm) and trying to write on most of that area. I use the standard clips and I
> notice that it's hard to keep the focus over such area. Can I use the piezos
> for this purpose, or the piece is too small? what's the standard position of
> the piezos, for which the stage itself is flat? Should I "center the piezos"
> at the beginning of the session or leave them as they are after the warm up?
> Thanks!
>
> The leveling piezo's are intended to level larger samples/wafers (2.5" and
> greater).  As far as starting with a level sample holder...the Universal
> Sample Holder itself was not machined to the level of accuracy needed for
> leveling with these piezo's.  In general, the system admin must go through
> the calibration procedure for each sample holder.  In the window "Height
> Control", you can select the sample holder you are using, then select
> "LEVEL".  This should adjust the piezo's to the pre-calibrated values.
> Before the recent service issues with the column, James was planning on
> calibrating the electro-static chuck.  Once this is done, you will be able
> to level entire wafers.  Another idea...if you are using the clips to secure
> your sample, try using larger samples.  The further in the clip is on your
> sample, the less the sample will tilt.
>
> When James returns, ask him if he has calibrated the piezo's in the Height
> Control window.  In the meantime, I would center the piezo's after loading a
> sample.
>
>
>
> I'll write/call you tomorrow after developing tonight's sample. Regards
> Luigi
>
>
>
>
>
>






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